Or, "How I upped my geek cred one morning for $90 in parts and a little moxie."

As a "maker" n00b, I can’t express how awesome it is to build a homemade solar-powered iPhone charger. The little 2W solar panel currently sits in the window of my west-facing home office (more on that later). Now, every afternoon, as the sun starts blazing onto my desk, I soak up a little power.

I know probably hundreds (or maybe thousands) of people have built similar chargers before. After all, 20,000 people attended the first San Francisco Maker Faire in 2006, and it's only grown since. Nationwide, there are tens or hundreds of thousands of makers out there. But there are probably plenty more would-be DIYers who are intrigued but haven't yet taken the plunge. I’m here to tell those people that for just $90 in parts and three hours of time, you too can keep your iPhone going, wherever you go. Seriously.

1% inspiration: Getting started

I know what you're thinking. Sure, I could just get an official Apple charger for $30. Maybe there's a third-party option for less. And yes, I could throw down $80 for a Mophie Juicepack to meet my external battery desires. But where's the fun or satisfaction in any of that?

More Ars-approved DIY Projects

Until last week, I was one of those people who admired the craftsmanship involved in many DIY projects, but thought that they were a bit too involved for me. I've always felt that wordsmithing—rather than electrosmithing—is my best skill. I mean, sure, I've swapped some RAM on my own computer before, but nothing that involved a heat gun and melting metal! But you really don't need any background to start. It only takes an idea.

I loved the idea. He keeps his phone charged and doesn't have to think about it. My phone constantly runs low. I pretty much have to carry a charger with me when I'm on the run. If I get really power-conscious, I go into no-Internet/no-GPS mode. If I'm really desperate—here comes Airplane Mode, turning it off again just to quickly send/receive text messages.

Ever since I saw Martinet's, I couldn't shake the thought. How cool would it be to have a similar setup?

Enlisting help and assembling the pieces

Earlier this summer, I mentioned this idea to my friend Malcolm Knapp, an electrical engineer here in Berkeley. Malcolm didn’t think it would be terribly difficult. A few Google searches proved him correct. Not only was it not difficult, but back in 2009, someone already put together a nice Instructables page outlining each step. To boot, it has a cutesy name: the MightyMintyBoost. Crucially, the page includes a shopping list (crucially, because, I didn't find the instructions Martinet gave me until well after completing this project).

Of course, Instructables or a knowledgeable friend aren't the only places to get started. Websites like HackADay and magazines like Make offer great resources, too. So why did I eventually keep Malcolm involved? Mostly, I wanted his expertise for two reasons: first, to make sure I didn’t do any serious damage to myself or the electronics. And second, well, I don’t own a soldering iron. As the assistant organizer of MakeSF, Malcolm couldn’t have been a better teacher. And when we sought equipment help through the folks at Tech Liminal (an Oakland co-working space), we had a great place to do it.

Enlarge/ The MintyBoost comes with loose resistors, capacitors, and a diode.

Cyrus Farivar

Soldering 101

After waiting for all the parts to show up at my door (and for Malcolm to get back from his honeymoon), we finally sat down last week to do this together. Here’s what we started with (taxes and shipping included, and we also had to sacrifice a Micro USB cable that was kicking around):

With all the parts gathered, it was time to assemble the MintyBoost. This little green circuit board, first designed way back in 2006, is meant to take in power from batteries or solar panels and "boost" power to the 5V that the iPhone is made to take. When it arrived in the mail, it was just a bunch of loose wires (I learned those were resistors and diodes), a female USB connector, and some padding. So, step one was to solder the resistors to the board.

"I always say that soldering is a three-hand job," Malcolm first told me, as he produced a weird little holding device. "And this, is called a ‘third hand.’"

In front of us was a little stand with clips that I could secure my MintyBoost to as I worked on it. Malcolm showed me how to bend the resistor legs down and thread them through the board. Then, carefully, I’d touch the soldering iron to the filaments and, voilà, sleek tin would flow onto the little pads on the board.

It got easier as I worked on it—and I quickly learned what happens when you mis-solder something (hint: you need to remove it). A spool of copper strips was produced, and through a combination of pressing heat to one side, the solder would jump to the copper.

The MintyBoost is alive

Once we’d finished assembling the MintyBoost—following essentially the same soldering steps for the four resistors, one diode, and two capacitors—it was time to wire it up to the LiPoly board.

"Now we have to do the ‘smoke test,’" Malcolm told me. "That basically means, if you see smoke, unplug everything—you’ve done something wrong."

No smoke, no fire, and we were well on our way. It took probably less than a minute to twist the electrical wires and connect all three elements of this setup to each other. Officially, this combination was the MintyBoost connected to the LiPoly, which in turn also connected to the already-charged battery. The moment of truth arrived and—it worked! Eureka! In less than two hours we had successfully created a functioning triad.

But I’d forgotten to get an Altoids tin. OK, it didn't have to be an Altoids tin. But I needed some sort of container to put the three electronic devices (the battery, the LiPoly converter, and the MintyBoost itself) into. So I ran a block down to the nearest liquor store to get an Altoids tin. Once I’d distributed the mints among the co-workers and had washed out the tin container, we needed to fix the cable feeding power out of the solar cell. Malcolm showed me how to take that Micro USB cable and splice it onto the cable coming out of the solar panel, so we could get power from the panel into the LiPoly charger, which would then feed power to the iPhone and to the battery.

And with that, it functioned, solar panel and all. Malcolm put the foam pads onto the two boards so they wouldn’t short in the Altoids tin, made a few cutouts for each port, and we were done.

And for my next trick...

All that’s left now is for me to adhere the boards and the battery to the Altoids tin; then I could easily keep the whole thing in my bag when I’m out and about. I also need to sort out how best to adhere it to my backpack if I want to mimic Martinet accurately; though maybe velcro strips or clasps of some kind will work fine.

So far, I haven’t had a chance to adequately test my MightyMintyBoost and see how many hours I need to leave it plugged in to fully charge my phone. In fact, after the first few days of trying to use the charger on my desk, it didn’t seem like it was fully getting adequate power. Frequently I’d get a "Charging is not supported with this accessory" error message on the phone, or it would alternate between charging and not.

So I rang up Jerome Kelty, a Colorado-based jeweler by trade and the author of that original Instructable. Kelty told me that I should use it primarily outside.

Want your own solar-powered charger?

Remember, Cyrus utilized this Instructables page. It's a simple five-step set of instructions, and the materials (soldering iron not included) cost under $100. Project run time: under three hours.

"Small panels like that, they pretty much have to be in direct, outdoor sunlight," he said. "If I have it in my kitchen window, it doesn’t work nearly as well."

He explained that being indoors simply doesn't draw enough power, and that anything blocking the light—windows, trees, shade—diminishes the current. The iPhone is also quite finicky about how much power it draws on its own.

Kelty said that this Instructable continues to get a lot of attention, and people still frequently leave him comments. He addresses every single one. Apparently I’m like a lot of DIY newbies out there.

"The MintyBoost is a great introduction to soldering," he added. "This is an extension of that. Basically all you’re adding is a circuit, but it’s a really good starting point."

Now that I've completed my first project, I feel confident in my abilities to do basic soldering and follow related instructions. I still am not 100 percent clear on what all the elements do, but Malcolm has been very patient with my sometimes inane questions. ("So, a capacitor is different than a resistor, right?")

I guess I'm ready to take my next step into the DIY world. I may not own a soldering iron yet, but I know that the nearest one is just a 10 minute bike ride away. Kelty suggested that for my next project, as a cyclist, I might try to tackle his "Ultimate Night Vision Headlamp"—it’s a cheap, lightweight, and crazy-bright light. This involves not only soldering, but gluing LEDs to an old CPU heat sink. (Coincidentally, I haven't been this excited about gluing since elementary school!)

So take note, Oakland. If you see someone wearing a ridiculous blue lamp on two wheels, you’ve been warned. There's a new, very junior member of the maker movement in the neighborhood.

It's not just an iPhone charger either. It has a USB port, so it should charge anything that charges over USB.

In my experience this doesn't work. I made a MintyBoost to charge my Garmin 305 in the back country. I had success in that it could charge devices, but it would not charge them to capacity. After a while the Garmin would simply shut off and forget it was plugged into the charger. I was left with a device that wasn't completely charged. This was my first Make attempt so I thought I screwed something up in the construction and built another one. It had the same results. The Minty article talks about how the resistors used on the board might be device dependent, and to get results for your particular electronics you might have to change things out.

111 posts | registered Jan 28, 2005

Cyrus Farivar
Cyrus is the Senior Business Editor at Ars Technica, and is also a radio producer and author. His latest book, Habeas Data, about the legal cases over the last 50 years that have had an outsized impact on surveillance and privacy law in America, is due out in May 2018 from Melville House. Emailcyrus.farivar@arstechnica.com//Twitter@cfarivar

Agreed. I have the interest and technical chops but not the follow-through. (Mainly, I solder like I have some kind of degenerative nerve disease.) Always cool to hear about such projects though. Occasionally they fire me up to the point of making an attempt.

Are there any kits that turn the back of your iPhone into a solar panel?

see a couple comments up from fferitt25 his link was a case that has a solar add on which is pretty sweet. Good article. I wish someone that had a kill a watt could post the values from charging a current gen smartphone to weigh the cost of parts vs actual electricity used.

Works better than the POS made-in-china solar charger I got. That thing charged neither the built-in batt nor any devices hooked up via USB.

However, I must say, when I first saw "Altoids" under the 1st pic caption, I just busted out laughing. Altoids is the unofficial mascot of Instructables. I wonder if Altoids realizes all the free publicity they get from kit-bashers.

It's not just an iPhone charger either. It has a USB port, so it should charge anything that charges over USB.

As I understand it, the LiPo charger has a USB *input*, so you can charge your LiPo using USB, but it does not charge devices over the USB (in other words, no USB out).

I really like (and I am using) the Adafruit Solar LiPo Charger (http://adafruit.com/products/390 no business relationship, just a customer), which is similar in intent to the charger board you list. AFAIK from looking at both the Sparkfun page for their product, and the Adafruit page for theirs, the USB does not reliably supply power. Indeed the Adafruit support materials explicitly say to unplug USB "from your computer" when charging the LiPo with solar.

Works better than the POS made-in-china solar charger I got. That thing charged neither the built-in batt nor any devices hooked up via USB.

However, I must say, when I first saw "Altoids" under the 1st pic caption, I just busted out laughing. Altoids is the unofficial mascot of Instructables. I wonder if Altoids realizes all the free publicity they get from kit-bashers.

Those metal tins are so damn useful! They're also musical, they come straight from the factory as a shaker, and if you shove them on the string board of a piano they make some AWESOME sound (look up Ben Folds Altoids for a demo).

It's cool and all - but I suppose these are for the sake of learning and doing.

For $90 in parts - I could just go buy a solar charger for $50 and splurge on something else w/ the other $40.

Yeah pretty much this. Its economics is the other side. The other issue which the article doesn't go into is most of these designs were only meant to pump out 250-500 mAh. A lot of smartphones now require 500 minimum to trickle charge or even just be used to maintain power and ignore charging.

I think people are forgetting just how poor the market was for on the go charging when these things became available. Portable solar panels and battery packs sporting USB weren't nearly as common in 2006 as they are now and about all I can remember are those little emergency battery packs.

As technology marches on older things often get cheaper, more available, and more powerful. But there is always more to do and the skills gained in doing something like this can be applied elsewhere and even for original designs.

You might be able to buy the same thing mass produced for $30 but for his money he got a lesson in soldering, basic electronics construction, hopefully lost his phobia of tinkering with expensive gadgets, and made a charger with a bit more personality. He's also already talking about moving on to more complicated projects by the end of the article.

It's not just an iPhone charger either. It has a USB port, so it should charge anything that charges over USB.

In my experience this doesn't work. I made a MintyBoost to charge my Garmin 305 in the back country. I had success in that it could charge devices, but it would not charge them to capacity. After a while the Garmin would simply shut off and forget it was plugged into the charger. I was left with a device that wasn't completely charged. This was my first Make attempt so I thought I screwed something up in the construction and built another one. It had the same results. The Minty article talks about how the resistors used on the board might be device dependent, and to get results for your particular electronics you might have to change things out.

Great story and thanks for the references that enable us to make our own versions! DIY will have a major role in the future economy. Keep the articles coming and share the resources. Adafruit and Sparkfun are fantastic. Consider an article about Hack-a-day...http://hackaday.com/

I am yet another "want to get into the 'maker' thing, not sure where to start" person, so this article was a bit inspirational to read. I'd definitely welcome more of this type of article (potentially with project ideas costing less than $90 to start...).

DIlbert, I found this link after researching for DC power meters. I didn't find any DIY kits that could be used yet, but these "battery checker" devices could be integrated into this project:http://www.logicrc.com/?s=c:0,c:50,c:50-70

I am yet another "want to get into the 'maker' thing, not sure where to start" person, so this article was a bit inspirational to read. I'd definitely welcome more of this type of article (potentially with project ideas costing less than $90 to start...).

Check around for advice on resistor values for specific devices and mod the board with 3 different resistors going through a 3 pole micro switch. Pick a value, throw the switch, and charge into that good night.

At the risk of sounding like an ass...No! No more DIY stuff! I've enjoyed reading Ars because it typically has a more educated audience often populated with people knowledgeable about the topics being discussed, not the typical simplistic discussion of other tech related sites. You know who I mean.

As an EE, I can't stand this whole "I followed an internet article telling me how to hook up a boost converter then replaced the batteries with a solar cell" sort of articles. I'm all for people educating themselves and wholeheartedly believe that tinkering in ways such as this is an indispensable part of the process. But I don't want to read about it any more that I want to read "student goes to class, learns how to do something useful." PLEASE keep this site the more technical sort of place that I've come to expect.

Sure, the author should be commended for making an effort to create something... it's a nice first step, but it's not exactly MAKING something.

Is putting together a jigsaw puzzle or assembling a plastic model "MAKING" something. No IMHO it's not. It's just assembly work. A 7 year old child can do that (and in some third world countries they do it for a living :-O)

MAKING something to me, means creating something unique that one had to design. It could be a charger, but one cobbled together from spare parts found around one's house, not "log onto internet, buy overly expensive kit, assemble kit"

For those who don't feel like tinkering in this area, the Tekkeon TekCharge is a good option. With a good set of 4 AA NIMH low self-discharge batteries, it's still under a total of $30, and it will fully charge a new iPhone. You don't even need a separate charger, as it will act as one if plugged into a USB port, but be mindful of the time, as the charge controller is not smart.

In a pinch, you can also buy 4 alkaline AA at the corner store. Not so ecological, but it will get you about 3/4 charged.

I made a battery powered USB charger using 4 AA holder, an USB extension cable and 4 NiMh cells. Just cut an USB extension cable. The wires are supposed to be color coded. Red to plus, black to minus. The two remaining are data, these can be connected to each other to tell the phone that i may pull 2 A. I have used it on many phones including iphone.

Sure, the author should be commended for making an effort to create something... it's a nice first step, but it's not exactly MAKING something.

Is putting together a jigsaw puzzle or assembling a plastic model "MAKING" something. No IMHO it's not. It's just assembly work. A 7 year old child can do that (and in some third world countries they do it for a living :-O)

MAKING something to me, means creating something unique that one had to design. It could be a charger, but one cobbled together from spare parts found around one's house, not "log onto internet, buy overly expensive kit, assemble kit"

I'm glad it's somebody else knocking the wind out of sails today and not me!

It's not just an iPhone charger either. It has a USB port, so it should charge anything that charges over USB.

In my experience this doesn't work. I made a MintyBoost to charge my Garmin 305 in the back country. I had success in that it could charge devices, but it would not charge them to capacity. After a while the Garmin would simply shut off and forget it was plugged into the charger. I was left with a device that wasn't completely charged. This was my first Make attempt so I thought I screwed something up in the construction and built another one. It had the same results. The Minty article talks about how the resistors used on the board might be device dependent, and to get results for your particular electronics you might have to change things out.

I agree...I have yet to find a USB charger for my Nokia N9 that charges it sufficiently. Of course the Nokia charger that came with it does, but if I plug it into any other the phone reports that there is not enough power to charge the device.

This looks like a great project. I'd really love to adapt it with a handlebar mount so I can use my iPhone as a track recorder while mountain biking without killing the battery.

Personally, I'd find a project that transformed the mechanical energy of the bicycle into a charger more useful. If you could hit a switch to activate regenerative braking for downhill, you could probably charge up your iPhone even more easily.

At the risk of sounding like an ass...No! No more DIY stuff! I've enjoyed reading Ars because it typically has a more educated audience often populated with people knowledgeable about the topics being discussed, not the typical simplistic discussion of other tech related sites. You know who I mean.

As an EE, I can't stand this whole "I followed an internet article telling me how to hook up a boost converter then replaced the batteries with a solar cell" sort of articles. I'm all for people educating themselves and wholeheartedly believe that tinkering in ways such as this is an indispensable part of the process. But I don't want to read about it any more that I want to read "student goes to class, learns how to do something useful." PLEASE keep this site the more technical sort of place that I've come to expect.

First, the DIY movement is an important part of what's happening in technology now IMHO, and so it's legitimate news which I'd expect Ars to cover. Second, I and clearly others like reading about it (see above). And third, I have no idea what "technical sort of place" you think Ars is now where articles about building circuits are improper. We have, currently, photoessays on the space shuttle, chats about videogames, lots of play by play smartphone wars stuff, copyright and patent coverage, but very little 'technical' articles to be seen. Maybe you're remembering a bygone era?

And last, I would HOPE that not only would ACTUAL EE's, who us backyard hackers generally admire and look up to (when you're not dismissively avoiding reading about our attempts to learn a little about your world) would participate in the discussion, but be happy to lend their considerable wisdom. What better place than Ars to elevate the discussion, since we have such educated commenters? Don't be elitist, teach us the benefit of your wisdom!

For example, real EE's could helpfully point out in the comments why the mintyboost doesn't work on some types of smartphones and how we can fix it. Hint hint. Cause I'd like to know.

At the risk of sounding like an ass...No! No more DIY stuff! I've enjoyed reading Ars because it typically has a more educated audience often populated with people knowledgeable about the topics being discussed, not the typical simplistic discussion of other tech related sites. You know who I mean.

As an EE, I can't stand this whole "I followed an internet article telling me how to hook up a boost converter then replaced the batteries with a solar cell" sort of articles. I'm all for people educating themselves and wholeheartedly believe that tinkering in ways such as this is an indispensable part of the process. But I don't want to read about it any more that I want to read "student goes to class, learns how to do something useful." PLEASE keep this site the more technical sort of place that I've come to expect.

First, the DIY movement is an important part of what's happening in technology now IMHO, and so it's legitimate news which I'd expect Ars to cover. Second, I and clearly others like reading about it (see above). And third, I have no idea what "technical sort of place" you think Ars is now where articles about building circuits are improper. We have, currently, photoessays on the space shuttle, chats about videogames, lots of play by play smartphone wars stuff, copyright and patent coverage, but very little 'technical' articles to be seen. Maybe you're remembering a bygone era?

And last, I would HOPE that not only would ACTUAL EE's, who us backyard hackers generally admire and look up to (when you're not dismissively avoiding reading about our attempts to learn a little about your world) would participate in the discussion, but be happy to lend their considerable wisdom. What better place than Ars to elevate the discussion, since we have such educated commenters? Don't be elitist, teach us the benefit of your wisdom!

For example, real EE's could helpfully point out in the comments why the mintyboost doesn't work on some types of smartphones and how we can fix it. Hint hint. Cause I'd like to know.

Well said ayemuhnurd. As an EE (as if that means anything apart from having sat in classes for 4 years), I think it's fantastic that somebody had the wherewithal to go from not knowing what resistors were (it came with a bunch of wires - I LOLd!), to assembling a DIY solar charger. It may be a relatively simple project, but the attitude is there. Who knows, he might solve the 'charging for multiple device types' issue with a little effort, and send in a rev for the board!

FWIW, it sounds like a current issue - some devices will need more current to charge properly. Get out a multimeter and see what you're getting out of this thing.

At the risk of sounding like an ass...No! No more DIY stuff! I've enjoyed reading Ars because it typically has a more educated audience often populated with people knowledgeable about the topics being discussed, not the typical simplistic discussion of other tech related sites. You know who I mean.

As an EE, I can't stand this whole "I followed an internet article telling me how to hook up a boost converter then replaced the batteries with a solar cell" sort of articles. I'm all for people educating themselves and wholeheartedly believe that tinkering in ways such as this is an indispensable part of the process. But I don't want to read about it any more that I want to read "student goes to class, learns how to do something useful." PLEASE keep this site the more technical sort of place that I've come to expect.

First, the DIY movement is an important part of what's happening in technology now IMHO, and so it's legitimate news which I'd expect Ars to cover. Second, I and clearly others like reading about it (see above). And third, I have no idea what "technical sort of place" you think Ars is now where articles about building circuits are improper. We have, currently, photoessays on the space shuttle, chats about videogames, lots of play by play smartphone wars stuff, copyright and patent coverage, but very little 'technical' articles to be seen. Maybe you're remembering a bygone era?

And last, I would HOPE that not only would ACTUAL EE's, who us backyard hackers generally admire and look up to (when you're not dismissively avoiding reading about our attempts to learn a little about your world) would participate in the discussion, but be happy to lend their considerable wisdom. What better place than Ars to elevate the discussion, since we have such educated commenters? Don't be elitist, teach us the benefit of your wisdom!

For example, real EE's could helpfully point out in the comments why the mintyboost doesn't work on some types of smartphones and how we can fix it. Hint hint. Cause I'd like to know.

As you would hope, not all of us EEs feel our knowledge/experience/elitism is somehow offended by people learning electronics; I for one am hugely excited that many people outside of formal electrical/electronic education are getting interested in what's inside the many gadgets and devices they use every day.

Is the story of somebody building a solar-powered mintyboost technically impressive? Not really. Is the story of somebody who has no (formal or informal) electronics experience taking the initiative to learn what he needs to take on the project and to stick with it to completion impressive? Absolutely! I know that this kind of stuff is daunting to those less familiar with it, but it's not something to be afraid of; it's something to be explored. Anything that motivates people to learn about and understand the world around them (and to give themselves some self-sufficiency to boot) is fantastic in my books.

About your charging/not charging various devices problem, my guess is it's either simply a current problem (lots of USB-charged devices want to draw a lot more than what a normal USB port is spec'ed for or a mintyboost is designed to provide), your power source (battery or solar panel) isn't providing the minimum 2V that the boost converter chip requires to run properly, or the sense resistors on the data lines (R1 through R4) aren't making the device happy.

In the latter case, you can try removing them entirely (might work on some stuff) or you can try adding a 200-ohm resistor between the two data lines as per http://blog.curioussystem.com/2010/08/t ... -charging/Every manufacturer seems to have their own idea for what the device expects from the data lines of a device hooked up to a charger instead of a PC; that article even describes a slightly different set of resistors used for iPods than the one used in the mintyboost that produces a slightly higher voltage on the D+ pin. You can try replacing the 75K R2 with a 43K if you want to give that a shot as well.

It's not just an iPhone charger either. It has a USB port, so it should charge anything that charges over USB.

In my experience this doesn't work. I made a MintyBoost to charge my Garmin 305 in the back country. I had success in that it could charge devices, but it would not charge them to capacity. After a while the Garmin would simply shut off and forget it was plugged into the charger. I was left with a device that wasn't completely charged. This was my first Make attempt so I thought I screwed something up in the construction and built another one. It had the same results. The Minty article talks about how the resistors used on the board might be device dependent, and to get results for your particular electronics you might have to change things out.

Yes, because some devices will require a specific voltage to recognize they are connected to a charger, it may indeed be a matter of changing the resistors.

I won't try to school you on basic electronics, but in a nutshell, devices that run off of USB can use anywhere from about 1-5V, but they will require a "trigger" voltage to be met to start charging.

Portable devices like iPods and phones usually require about 1-3V @50-200mA for charging.

The reason your device may not recognize the charger is due the fact that a certain voltage is required for the device to see a "1", meaning it would see any power from the charger as electronic noise until it had reached that voltage threshold until which point it sees a "0"; the switch won't flip at 8.5V, it will only flip once 9V is reached (example).

You could use a multimeter to test the voltage output of the charging device and compare this with the voltage listed on the stock adapter. Using V=IR (Ohm's law, where V=voltage, I=amps and R=Resistance) you could figure out which resistor values need to be lowered.

In all likelihood, if you simply design the device to put out the maximum voltage of a standard USB 2.0 port (5V +/- 25%) and then use a potentiometer to regulate amperage (this is what will destroy your device, not voltage) this would be a much more useful charging device.

At the risk of sounding like an ass...No! No more DIY stuff! I've enjoyed reading Ars because it typically has a more educated audience often populated with people knowledgeable about the topics being discussed, not the typical simplistic discussion of other tech related sites. You know who I mean.

As an EE, I can't stand this whole "I followed an internet article telling me how to hook up a boost converter then replaced the batteries with a solar cell" sort of articles. I'm all for people educating themselves and wholeheartedly believe that tinkering in ways such as this is an indispensable part of the process. But I don't want to read about it any more that I want to read "student goes to class, learns how to do something useful." PLEASE keep this site the more technical sort of place that I've come to expect.

First, the DIY movement is an important part of what's happening in technology now IMHO, and so it's legitimate news which I'd expect Ars to cover. Second, I and clearly others like reading about it (see above). And third, I have no idea what "technical sort of place" you think Ars is now where articles about building circuits are improper. We have, currently, photoessays on the space shuttle, chats about videogames, lots of play by play smartphone wars stuff, copyright and patent coverage, but very little 'technical' articles to be seen. Maybe you're remembering a bygone era?

And last, I would HOPE that not only would ACTUAL EE's, who us backyard hackers generally admire and look up to (when you're not dismissively avoiding reading about our attempts to learn a little about your world) would participate in the discussion, but be happy to lend their considerable wisdom. What better place than Ars to elevate the discussion, since we have such educated commenters? Don't be elitist, teach us the benefit of your wisdom!

For example, real EE's could helpfully point out in the comments why the mintyboost doesn't work on some types of smartphones and how we can fix it. Hint hint. Cause I'd like to know.

As you would hope, not all of us EEs feel our knowledge/experience/elitism is somehow offended by people learning electronics; I for one am hugely excited that many people outside of formal electrical/electronic education are getting interested in what's inside the many gadgets and devices they use every day.

Is the story of somebody building a solar-powered mintyboost technically impressive? Not really. Is the story of somebody who has no (formal or informal) electronics experience taking the initiative to learn what he needs to take on the project and to stick with it to completion impressive? Absolutely! I know that this kind of stuff is daunting to those less familiar with it, but it's not something to be afraid of; it's something to be explored. Anything that motivates people to learn about and understand the world around them (and to give themselves some self-sufficiency to boot) is fantastic in my books.

About your charging/not charging various devices problem, my guess is it's either simply a current problem (lots of USB-charged devices want to draw a lot more than what a normal USB port is spec'ed for or a mintyboost is designed to provide), your power source (battery or solar panel) isn't providing the minimum 2V that the boost converter chip requires to run properly, or the sense resistors on the data lines (R1 through R4) aren't making the device happy.

In the latter case, you can try removing them entirely (might work on some stuff) or you can try adding a 200-ohm resistor between the two data lines as per http://blog.curioussystem.com/2010/08/t ... -charging/Every manufacturer seems to have their own idea for what the device expects from the data lines of a device hooked up to a charger instead of a PC; that article even describes a slightly different set of resistors used for iPods than the one used in the mintyboost that produces a slightly higher voltage on the D+ pin. You can try replacing the 75K R2 with a 43K if you want to give that a shot as well.

I think people are forgetting just how poor the market was for on the go charging when these things became available. Portable solar panels and battery packs sporting USB weren't nearly as common in 2006 as they are now and about all I can remember are those little emergency battery packs.

As technology marches on older things often get cheaper, more available, and more powerful. But there is always more to do and the skills gained in doing something like this can be applied elsewhere and even for original designs.

You might be able to buy the same thing mass produced for $30 but for his money he got a lesson in soldering, basic electronics construction, hopefully lost his phobia of tinkering with expensive gadgets, and made a charger with a bit more personality. He's also already talking about moving on to more complicated projects by the end of the article.

And even if he doesn't, he'll still be that little bit more sceptical/critical of "techno-magical" explanations and justifications for why he should be so happy to let large corporations shamelessly exploit his ignorance... just because it's "technology".